Connecting means for heat exchanger cores



United States Patent signors to The Trane Company, La Crosse, Wis., a

corporation of Wisconsin Filed Jan. 21, 1964, Ser. No. 339,134 6 Claims. (Cl. 165166) This invention relates to apparatus for connecting heat exchangers in series and is particularly applicable to heat exchangers of the brazed plate fin type such as brazed aluminum plate fin heat exchangers.

Such heat exchangers are frequently used in cryogenic processes for the separation of various fluid compounds and elements from gases such as air and natural gas. Nitrogen, oxygen and helium are exemplary products of such processes.

Generally these processes employ heat exchangers for transferring heat from the incoming raw gaseous fluid to the already cooled, refined and separated fluid product as well as to any cooled waste products. In other words, the cold content or value of the outgoing products is recovered to cool incoming raw fluid. Process heat exchangers of this type are operated at temperatures ranging from room temperature down to and below the liquification temperature of nitrogen or about 320 F. Heat exchangers operating under these extremely cold temperatures are normally mounted in a room or box which is filled with an insulating material. Such rooms or boxes are known to the art as cold boxes.

Since there are practical limitations as to the size in which brazed heat exchanger cores may be manufactured, it becomes necessary in some processes requiring large heat transfer surfaces to join the streams of several brazed heat exchanger cores in series. This is conventionally done by providing each stream of each heat exchanger with a header which is joined serially by a conduit to the header of a like stream of the next heat exchanger core. Such headering arrangements increase the over-all length of multiple core combination and thus increase the size of the cold box required. Further, conventional headering arrangements add considerably to the pressure drop across the multiple core combination. It is desirable in many processes to keep the pressure drop in at least one stream to a minimum.

It is thus an object of our invention to provide means for connecting the streams of several plate type heat exchanger cores in a novel and improved manner.

It is a further object of our invention to join a pair of streams of separate heat exchanger cores with only a single header.

Another object of the invention is to provide a means for joining several heat exchanger cores in series in an end-to-end fashion whereby the insulating cold box may be made relatively small and the pressure drop in the streams is kept to a minimum.

A further object of our invention is to provide a core connecting means of high operating efficiencies and low cost which is particularly suitable for plate type heat exchanger cores of aluminum construction.

Another object of our invention is to provide a multiple heat exchanger core combination which approximates the length of a single heat exchanger core having a similar core cross section and equivalent total heat exchange surface.

Still another object of this invention is to provide structure of unique construction for removing a portion of the heat exchange fluids from the side of and between the ends of aplate type heat exchanger core means.

Other objects and advantages of our invention will be come apparent as this specification procedes to describe 3,266,568 Patented August 16, 1966 the invention with reference to the accompanying drawings in which:

FIGURE 1 is a side elevation of two brazed plate type heat exchanger cores secured end-to-end by our novel core connecting means with a portion thereof broken away to show the core connection.

While the longitudinal axis of the core complex is shown horizontally, it may be vertically disposed if desired.

FIGURE 2 is a side elevation taken at line 2--2 of FIGURE 1 with a portion of a header thereof broken away;

FIGURE 3 is an enlarged sectional view of a portion of the heat exchanger core connecting means taken at line 33 of FIGURE 2;

FIGURE 4 is an enlarged sectional view of a portion of the heat exchanger core connecting means taken at line 44 of FIGURE 2;

FIGURE 5 is an enlarged sectional view of a portion of the heat exchanger core connecting means taken at line 55 of FIGURE 2;

FIGURE 6 is a sectional view of the heat exchanger core connecting means taken at line 66 of FIGURE 1; and

FIGURE 7 is a greatly enlarged sectional view of a sealing weld detail shown in FIGURE 6.

Referring to the form of the invention shown in FIG- URES 1-7, it will be seen that the heat exchanger complex 10 is comprised of first and second elongated plate type brazed aluminum heat exchanger cores 12 and 14, respectively, joined end-to-end by connecting structure generally designated by numeral 16.

Each core is generally rectangular in form and comprises a stack of spaced parallel rectangular planar aluminum separating or parting sheets 18. These sheets separate the several heat exchange fluid streams in the core, as will be discussed, and function to transfer heat between said several streams. Outward of the parting sheets in spaced parallel relationship therewith are arranged a pair of rectangular side sheets 20 to retain the fluids within the core.

Between the separating or parting sheets 18 at the periphery thereof and between the outermost parting sheets and the side sheets 20, also at the periphery thereof, are arranged side closing members 22 and end closing members 24 which may take the form of elongated bars or channels. Each pair of parting sheets or outer parting sheet and adjacent side sheet thus defines therebetween in cooperation with the side and end closing members a flat rectangular cavity or fluid passage. Ingress and egress of heat exchange fluid to and from each passage is by way of openings or ports in the closing members as will be described in greater detail in connection with each of several different groups of passages.

Also there may be arranged between the parting sheets 18 and between the outermost parting sheets and the adjacent side sheets 20 in the cavity or passage thus defined, extended heat transfer surface such as for example a corrugated fin packing 26 as shown in US. Patent 2,961,222 to enhance the heat transfer characteristics of I the core and to assist in supporting the parting sheets.

adjacent the outer end of core 12 and headers 34, 36, and 38 connected adjacent the outer end of core 14.

The panticular header arrangement employed at the outer ends of the core complex 16) may be entirely conventional and does not per se constitute a part of our invention.

It will be further understood that the headers above mentioned may be placed on the core any time during the construction including before or after the brazing operation above referred to, or before or after the several cores are joined end-to-end as will be described.

The group of passages associated with each stream or header are arranged between or adjacent passages of another group of passages associated with one or more of the other headers in order to obtain heat transfer between the heat exchange fluids passing in the several streams.

The core passages 29 associated with header 28 of core 12 and header 34 of core 14 have side openings or ports 40 and 42 respectively as seen in FIGURES 2 and 3 formed by the termination of side closing members 22 short of the end closing member 24 thereof.

In like manner core passages 43 associated with header 30 of core 12 and header 36 of core 14 have side openings or ports 44 and 46 respectively as seen in FIGURE 4 formed by the termination of side closing members 22 short of end closing members 24 thereof. Openings 44 and 46 are on the opposite side of the heat exchanger complex from openings 40 and 42. A corrugated distributor fin material 48 may be arranged to direct heat exchange fluid through said side openings or ports generally normal to the longitudinal axis of the heat exchanger cores.

The core passages 49 associated with headers 32 and 38 have end openings or ports 50 and 52 respectively (FIGURE 5) as no end closingmember is provided at the inner end of these passages. The passages associated with headers 32 and 38 are so arranged that end openings 50 and 52 are in alignment when cores 12 and 14 are placed end-to-end. While the cores 12 and 14 are held in this end-to-end position, the passages associated with header 32 are connected to the passages associated with header 38 simply by providing a circumferential weld 54 around the cores at the inner ends. Weld 54 traverses the inner ends of side sheets 20 as seen in FIGURES 6 and 7 and the broken away portion of FIGURE 1 and traverses closing members 22 and 24, as seen in FIG- URES 6 and 7 and the broken away portion of FIGURE 2. End closing members 24 prevent any fluid communication within the heat exchanger complex between passages 49 and the passages 29 and 43.

Thus, the connection of end openings or ports 50 and 52 of the several cores is made without the need of a header and heat exchange fluid may pass straight through with a minimum of deviation or deflection and with a low pressure drop.

Openings or ports 40 of core 12 are connected to openings or ports 42 of core 14 via a single header 56 While openings or ports 44 of core 12 and openings or ports 46 of core 14 are connected via a single header 58.

Each of headers 56 and 58 is comprised of a rectangular plate member 64 curved with a substantially constant radius of curvature about an axis extending in parallel relation to the longitudinal axis of the heat exchanger complex. The curve of each plate member subtends an angle of approximately 155 and is concave inward toward the heat exchanger complex. The innermost edges of plate members 64 are first secured to the cores along each side corner thereof as by longitudinally extending sealing welds 62 as will be seen in FIGURES 6 and 7. A header end closing plate member 68 having one arcuate edge and one straight edge is disposed at each end of each curved plate member 64. Plate members 68 are sealin-gly welded to the curved edges of plate member 64 and to the side of cores 12 and 14 to form an 4 enclosure sealed except for fluid communication with the passage side openings of the two cores and a bleed tube yet to be described. Thus openings 40 and 42 are connected by a single header 56 and openings 44 and 46 on the opposite side of the heat exchanger complex are connected by a single header 58.

Subsequently flat side plates 60 are arranged in the position shown slightly spaced from the core outer side sheets 26 and welded to the inner edges of curved plate members 64 by four separate longitudinally extending heavy structural welds 66. Side plates 60 through welds 66 provide one of the main structural supports for headers 56 and 58. While side plates 60 are welded indirectly at 62 to side sheets 20, weld 62 is merely a light sealing weld and not intended to anchor plates 60. Each plate 60 is fully anchored to side sheets 20 of the two cores by weld 74 along the edge of tab portions 76 of each side sheet which extend longitudinally outward beyond headers 56 and 58 to an area remote from the center of the core complex and remote from that area incorporating the passage openings or ports. If sealing welds 62 which are close to these ports were relied upon to anchor headers 56 and 58 and side plates 60, side sheets 20 would pull away at its edges from the cores due to the discontinuities of the cores in the areas adjacent the passage openings or ports where the structural continuity of the core is interrupted. By anchoring header curved member 64 to side plates 60 and then anchoring the side plates 60 to side sheets 20 in an area of weld 74 on tabs 76, this failure is avoided. It should be noted that the longitudinally extending portions of Weld 74 are located on side sheets 20 in an area where they are adequately supported by adjacent side closing members which in cooperation with the parting sheets form a solid and rigid side wall of the cores.

The heat exchanger disclosed in FIGURES 1-7 has been found particularly useful in cryogenic processes employing reversing streams, i.e. where passages 29 and 43 are alternately placed under high pressure. Should both headers 56 and 58 be subjected to the same pressure, the forces pushing one header away from the core are counterbalanced by similar forces from the other header transmitted through side plates 60. However, when the headers are alternately and not simultaneously placed under high pressure as in the case with reversing streams, the forces on the high pressure header must be transmitted to the core. The unique side plate arrangement with extended tabs 76 transmits a large portion of this load directly to the most sturdy portion of the core, i.e. the side walls comprised of the side closing members in an area where they are not interrupted to form the side ports. The stress is thus distributed within the core and the fin packing adjacent the side sheets is not subjected to undue stress reversal as the pressure is alternated from one header to the other.

Welds 62 aforementioned prevent heat exchange fluids from entering the space between side sheets 20 and side plates 66 permitting this space to be vented at 61 to the atmosphere so both sides of each side plate are subjected to atmospheric pressure whereby any tendency to buckle the side plates due to pressure differentials is avoided thus preserving the structural efliciency of the side plate members.

Curved members 64 and side plates 60 thus form a strong annular support member girding both cores in the area where they are joined as seen in FIGURE 6. As aforementioned, each core is anchored to this annular support member by weld 74 which is remote from the weaker portions of the cores such as adjacent the passage openings or ports. This annular support member is stronger and stiifer than the structural members of the cores by reasons of its thickness and the particular alloy selected.

A bleed tube 70 is installed through one of the closing plate members 68 anchored to the other closing plate member of each of headers 56 and 58. Tube 70 which may be used for sampling purposes is sealingly welded in this position and is provided with a slot 72 for receiving the fluid. It will be understood that the bleed tubes may be connected to a sampling apparatus or the like and that they provide additional support to closing plate members 68 to restrain the pressures within the headers.

Although we have described in detail preferred embodiments of our invention, we contemplate that many changes may be made without departing from the scope or spirit of the invention and we desire to be limited only by the claims.

We claim:

1. Heat exchanger apparatus comprising two elongated plate type cores connected together at one end wherein each core is substantially rectangular in cross-section normal to the longitudinal axis thereof and includes a plurality of elongated sheets disposed in superposed spaced relationship defining therebetween first and second groups of fluid passages, the outermost of said sheets defining first and second opposite sides of said core, the longitudinal edges of said sheets being coextensive with the third and fourth opposite sides of said core, means closing said passages at the peripheries thereof, each passage of said first group having an end port opening through said one end for communication with the end ports of the other core and each passage of said second group having a side port opening through said third side adjacent said one end; said cores being positioned in end-to-end relationship wherein said first, second, third, and fourth sides of one core are respectively substantially coplanar with the first, second, third, and fourth sides of the other core; a header extending longitudinally of the cores overlying the side ports of each core and terminating substantially short of the remote ends of said cores; means for transmitting a substantial portion of the force exerted by said header to said first and second sides of each core in areas longitudinally removed from said side ports and means sealingly separating said first ports from said second ports.

2. The apparatus defined by claim 1 wherein said force transmitting means comprises a first side plate extending longitudinally of said cores overlying said first sides, a second side plate extending longitudinally of said cores overlying said second sides, means anchoring said first and second side plates respectively to said first and second sides of each core in areas longitudinally removed from said side ports.

3. The apparatus defined by claim 2 wherein said header is cylindrical in form having a substantially constant radius of curvature about an axis extending parallel to the longitudinal axis of said cores.

4. The apparatus defined by claim 3 wherein said header is provided with a closing plate at each end thereof and a bleed tube connected to each closing plate extends through said header thereby serving to reinforce said header and function to withdraw a representative sample fluid therefrom.

5.- Heat exchanger apparatus comprising two elongated plate type cores connected together at one end wherein each core is substantially rectangular in cross-section normal to the longitudinal axis thereof and includes a plurality of substantially rectangular sheets disposed in superposed spaced relationship defining t-herebetween first, second and third groups of fluid passages, the outermost of said sheets defining first and second opposite sides of said core, the longitudinally extending edges of said sheets being coextensive with the third and fourth opposite sides of said core, means closing said passages at the peripheries thereof, each passage of said first group having an end port opening through said one end, each passage of said second group having a first side port opening through said third side adjacent said one end and each passage of said third group having a second side port opening through said fourth side adjacent said one end; said cores being positioned in end-to-end relationship wherein said first, second, third, and fourth sides of one core are respectively substantially coplanar with the first, second, third, and fourth sides of the other core; a first plate extending longitudinally of said cores overlying said first sides, a second plate extending longitudinally of said cores overlying said second sides, means anchoring said first and second side plates respectively to said first and second sides of each core in areas longitudinally remote from said first and second side ports; a first header extending longitudinally of the cores overlying said first side ports of each core and terminating substantially short of the remote ends of said cores; a second header extending longitudinally of the cores overlying said second side ports of each core and terminating substantially short of the remote ends of said cores; means connecting said first header to said first and second side plates; means connecting said second header to said first and second side plates and means sealingly separating said first and second side ports from said end ports and separating said first side ports from said second side ports.

6. The apparatus defined by claim 5 wherein each of said headers is cylindrical in form having a substantially constant radius of curvature about an axis extending parallel to the longitudinal axis of said cores.

References Cited by the Examiner UNITED STATES PATENTS 1,669,062 5/1928 Menzel -167 2,566,310 9/1951 Burns et al. 165-167 X 2,595,457 5/1952 Holm et al. 165166 2,658,729 11/1953 Horwitz 165-7 2,846,198 8/1958 Sturges 165-166 X FOREIGN PATENTS 878,357 6/ 1953 Germany.

ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner.

T. W. STREULE, Assistant Examiner. 

1. HEAT EXCHANGER APPARATUS COMPRISING TWO ELONGATED PLATE TYPE CORES CONNECTED TOGETHER AT ONE END WHEREIN EACH CORE IS SUBSTANTIALLY RECTANGULAR IN CROSS-SECTION NORMAL TO THE LONGITUDINAL AXIS THEREOF AND INCLUDES A PLURALITY OF ELONGATED SHEETS DISPOSED IN SUPERPOSED SPACE RELATIONSHIP DEFINING THEREBETWEEN FIRST AND SECOND GROUPS OF FLUIID PASSAGES, THE OUTERMOST OF SAID SHEETS DEFINING FIRST AND SECOND OPPOSITE SIDES OF SAID CORE, THE LONGITUDINAL EDGES OF SAID SHEETS BEING COEXTENSIVE WITH THE THIRD AND FOURTH OPPOSITE SIDES OF SAID CORE, MEANS CLOSING SAID PASSAGES AT THE PERIPHERIES THEREOF, EACH PASSAGE OF SAID FIRST GROUP HAVING AN END PORT OPENING THROUGH SAID ONE END FOR COMMUNICATION WITH THE END PORTS OF THE OTHER CORE AND EACH PASSAGE OF SAID SECOND GROUP HAVING A SIDE PORT OPENING THROUGH SAID THIRD SIDE ADJACENT SAID ONE END; SAID CORES BEING POSITIONED IN END-TO-END RELATIONSHIP WHEREIN SAID FIRST, SECOND, THIRD, AND FOURTH SIDES OF ONE CORE ARE RESPECTIVELY SUBSTANTIALLY COPLANAR WITH THE FIRST, SECOND, THIRD AND FOURTH SIDES OF THE OTHER CORE; A HEADER EXTENDING LONGITUDINALLY OF THE CORES OVERLYING THE SIDE PORTS OF EACH CORE AND TERMINATING SUBSTANTIALLY SHORT OF THE REMOTE ENDS OF SAID CORES; MEANS FOR TRANSMITTING A SUBSTANTIAL PORTION OF THE FORCE EXERTED BY SAID HEADER TO SAID FIRST AND SECOND SIDES OF EACH CORE IN AREAS SEALINGLY SEPARATING SAID FIRST PORTS FROM SAID SECOND PORTS. 